As a conventional airless tire, a solid tire having a solid rubber structure is mainly used for an industrial vehicle. The tire having solid rubber structure is however large in mass and inferior in shock absorption. Therefore, the tire has not been adopted for a riding comfortability-critical passenger vehicle.
To improve the riding comfortability of such an airless tire in order to apply for also the passenger vehicle, a structure (hereinafter may be referred as a “spoke structure”) to connect the tread ring and the hub by the spoke arrayed in the radial fashion (see Patent Document 1, for example).
And the Patent Document 1 proposes a bonding adhesively between the tread ring and the spoke and between the spoke and the hub. In this instance, it is possible to sufficiently ensure the bonding strength through a proper selection of the adhesive agent, and it is possible to exert necessary drag to load (up-and-download, back-and-forth force, lateral force and the like) in use as a tire.
However, when the airless tire mounted on an actual vehicle to run numerously, there are phenomenons such that sand and stone and the like on a road hit the tire and that the tire contacts with a curbstone when parking. This hit and contact do not have special trouble as far as they hit the spoke it self, the tread ring itself or the hub itself. However, they infrequently hit a bonding portion between the spoke and the tread ring and/or the bonding portion between the spoke and the hub, thereby damaging an outer end portion of an adhesion layer. Once this damage generates, the sand and grave stone and the like go into an interspace of the damaged portion, and the damage gets worse gradually. Then, it provokes flaking between the spoke and the tread ring and/or the spoke and the hub; therefore it deteriorates the durability of the tire.
To prevent this flaking, it is necessary to more improve at least the bonding strength itself between the spoke and the tread ring and/or the bonding strength itself between the spoke and the hub to inhibit the growth of damage.